When harvesting crops from agriculturally cultivated plants in a field, it is common practice for a harvesting machine to load a transport vehicle with harvested crops that moves next to the harvesting machine. A loading container of the transport vehicle, for example a tractor with a trailer or a truck is loaded by a transfer device of the harvesting machine, with the harvested crops, while the harvesting machine is moving about, for example with a forage harvester, through a discharge chute, and with a combine harvester, through a discharge spout. The transfer device is typically affixed on the harvesting machine around a vertical axis, so that it can rotate and swivel between a position at rest, in which it is oriented more or less parallel to the longitudinal axis of the harvesting machine, and a working position, in which it extends transverse to the direction of movement of the harvesting machine. In addition, the height of the discharge end of the transfer device can be varied, as well as the position of a discharge flap, which defines the angle at which the harvested crops are discharged.
With transfer devices that cannot be adjusted in their discharge position, as they are usually found on combine harvesters, the driver of the transport vehicle has to ensure that the filling of the loading container is uniform and complete by gradually putting the loading container beneath the loading device in different positions. This task is relatively demanding and tiring, since crop losses due to the crops failing on the field are to be avoided.
With adjustable loading devices as they are typically found on forage harvesters, the position of the transfer device is, in the simplest case, manually controlled by the driver of the harvesting machine, for which purpose input devices are available in the cabin, which control the actuators used to adjust the transfer device. The driver of the harvesting machine has to ensure that the entire loading container of the transport vehicle is sufficiently filed, which takes place by the successive alignment of the transfer device at different points on the loading container. If the transport vehicle should deviate forwards or backwards or to the site from its target position, the position of the transfer device has to be readjusted manually. It is disadvantageous that the control of the position of the transfer device takes up a considerable part of the attention of the driver, which leads to tiring work for the driver of the harvesting machine.
In order to avoid this disadvantage, systems have been proposed for the automatic filling of the trailer, which detect the optical features of the loading container by way of a camera and automatically adjust the position of the transfer device in such a way that the crops reach the loading container (DE 44 26 059 A1, EP 0 843 960 A1, EP 1 344 445 A1, and DE 10 2009 027 245 A1).
However, situations are conceivable in which such optical systems reach their limits-namely, in dusty environments, in poor lighting, or with obstacles between the camera and the loading container. In the state of the art, these systems immediately fail after an image that can be evaluated is no longer discernible, whereupon the operator of the harvesting machine has to switch to manual control of the transfer device so as to continue the harvesting operation. In switching to manual control, losses are, however hardly avoidable.